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| Non enhanced CT | CT angio |
Diagnosis: Basilar tip aneurysm
Most saccular aneurysms of the vertebrobasilar system occur at the basilar tip likely secondary to abnormal flow dynamics. Bleeding from a basilar tip aneurysm usually results in a symmetric distribution of hemorrhage within the subarachnoid space. Basilar tip aneurysms make up approximately 5% of all intracranial aneurysms. Saccular aneurysms, in general, have a cumulative risk of rupture of 1 to 2% per year.